Age related functional decline of nervous system is consistently observed, the sequence of causative molecular events for age related functional decline is unknown. This proposal focuses on possible roles of transmembrane Neuregulin-1 (Nrg-1) may have on this aging process. Our recent work revealed: (a) the cytoplasmic domain of Neuregulin-1 (Nrg-ICD) can translocate into the nucleus and regulate gene expression including that of PSD-95 and apoptotic genes;(b) Nrg-ICD regulates PSD-95 expression by binding to a transcription factor, Eos, and (c) during aging there is a correlation between nuclear translocation of Nrg-ICD and up-regulation of PSD-95 and BAK, a pro-apoptotic gene. The general hypothesis is that NRG-1 plays an essential role in age related neuronal changes. To test this hypothesis, we have made a conditional tissue-specific transgenic mouse model, which conditionally expresses Nrg-1 in several specific regions including hippocampus, spiral ganglion neurons, and outer-hair cells. By taking advantage of this mouse model, we will examine three related issues: (1) whether conditional overexpression of Nrg-1 in adult mice can alter age related hearing loss;(2) whether a conditional overexpression of Nrg-1 in adult mice can alter age related neuronal changes in hippocampus;(3) whether caloric restriction, the most effective way to delay the aging process, affects the role of Nrg-1 signaling pathways on age related neuronal changes. The ultimate goal of our research is to develop methods for prevention and treatment of age related functional decline of nervous system based on identifying molecular candidates involved in the aging process